Non-Optical and Sensory LVAs

These make the best use of residual vision/work via sensory substitution. Non-optical aids include daily living aids, environmental design, lighting and contrast and tints.

• Self threading needles, liquid level indicators, talking watches, large number telephones or microwaves, 'bump ons' or 'hi marks' and coloured stickers
• READING - making object bigger (large print books/bills/clocks/watches etc), talking watches or books or newspapers, reading stands, typoscopes, good lighting
• WRITING - felt tips, yellow paper, lined paper, writing frames

Braille was developed in 1824 and consists of 3x2 grid pattern of 6 dots giving 63 characters, 26 letters & contractions & punctuation. There are two levels - in grade 1 every word is spelt out and in grade 2 there are approved contractions for stuff like 'and' and 'with'. 20% of those registered blind can use braille. Books are thick and bulky and it isn't good for the elderly due to loss of sensation in their fingertips. It can be generated by a computer.

Moon is another tactile language that was developed in 1847. It was designed for people who previously had sight, featuring curves and lines that are more approximate to actual letters.

Electronic Aids for reading and writing

• CCTV, video magnifiers, head mounted devices
• Computers - scanners, speech synthesis, braille keyboards/printers, PDAs, USB cameras
• Built into OS - Windows has accessibility, Mac OSX has 'universal access' which enlarges icons, arrow, alters contrast and has voice output.
• Screen magnification software eg Zoomtext is also available.

Mobility Aids

• Canes and Sticks
• Electronic Aids (ultrasound, sonar)
• Dogs (see later)
• People (guides)
• Talking Signs
• Built Environment

White Sticks (if has red stripes this indicates px is deaf too)

1. Symbol Cane - lightweight, folds up, indicated px is VI
2. White walking stick - as above but aids support
3. Long Cane - most common. Developed by war vets in US following world war 2. Needs extensive training (+150hrs). Made of lightweight aluminium, held at chest height at 30 degree angle and swung in L to R arc as foot goes forward. Touches ground at end of travel and may have roller on tip
4. Guide Cane - Shorter/stronger than long cane, used as back up for those with residual vision

Trailing

Technique to help locate door, walk in straight line, detect posn of objects in front of the px on the same side of his body as the extended arm. This can provide useful info about everyday objects, obstacles and potential hazards. In familiar environment the px moves close to the wall with knuckles against it using the other hand in front to detect obstacles

Electronic Mobility Aids

• Ultrasonic - ultracane, hand held (miniguide, palmsonar), head mounted (sonic pathfinder), Bat K sonar-cane
• Laser - laser cane which has three beams (ground, waist, up) and alerts with tones and vibration
• GPS - MOBIC (mobility of blind and elderly people interacting with computers), braille note GPS, Trekker

Dogs

Guide dogs for the blind started in 1931. Running cost is 45m pa and they get no Govt funding. The dogs guide the owner and avoid obstacles, stop at kerbs/steps, find doors, road crossings and frequently visited places and lead across roads. The owner is basically responsible for encouraging the dog while directing and informing it.

Guide dog owners have to be over 16, have VI which makes safe independent travel difficult - marked decrease in VA, CS or VF. 43% of guide dog users are totally blind, mainly due to congenital or early onset degenerative disease. RP makes up 18% and optic atrophy 10%. The average age is 53.

Guide Dog Assessment

General Info Visit

• Info on services and training provided

Mobility Assessment

• Medical Status, cause and degree of VI, options (long cane or other, guide dog assess, non guide dog mobility aids)
• Contrainds - sufficient sight, age, dislike of dogs

Guide Dog Assessment

• Instructor assesses appropriate aid/suitability
• Work with dog to determine whether px can walk with it, follow movements, keep control, react etc
• Assessment of home environment

Breeding

1200 guide dogs are bred each year, mostly labs/lab-golden retr. cross. There has been a programme going since the 60s to reduce health probs and regulate supply. The dogs have x-ray health checks and eye exams

Makin the dog guide

• Puppy walking at 6 weeks old w/volunteer walkers who teach dog to ignore distractions or other dogs, walk on LHS and in straight line, centre of pavement, and stand and wait at kerb. 75% of puppies can do this, the other 25% are killed. No not really they are used as dogs for therapy, for the disabled, RAF, Customs & Excise, Prisons etc
• At 10-12 weeks the clever dogs go to a training centre where a proper dog trainer becomes involved, dog is fitted with harness and does tasks in busier environment etc
• At 3 months advanced training starts and dog is tailored to individ. needs

Pairing

Priority system. At 5 months dog attached to owner then 3-4 weeks intensive training, px taught to take care of dog. The owner pays a nominal 50p for the dog and the dog actually costs 35000 over its lifetime

Working

Continuing support is provided, with regular health checks, food/vet bills, third party insurance. Most dogs work 7-8 yrs. Guide dogs are allowed anywhere thanks to disability discrimination act 1995

Retiring

This is caused by health problems, increased mistakes, loss of concentration, slower walking speed, loss of confidence. The dog can stay with the owner as a pet or be rehoused.

Environmental Design

Simple things

• TV away from windows
• Sit close to TV/blackboard
• Location of reading lights
• At one side of teacher/TV if hemianopic px
• Colour schemes - Light paint on walls, dark round doors, lighter door with contrasting handle, dark flooring, hard flooring - for the sound, contrasting skirting boards for stairs

Architectural Design

• Features to aid VIPs eg lighting contrast
• Wide/sliding doors
• Auditory indicators eg in lifts
• Handrails
• Enclosed Staircases
• Tactile elements like on floors
• Avoid stuff like glass doors
  

LV: Lighting

Lighting

The goal of lightning is to provide adequate lighting in the appropriate places without any glare

• General lighting - there should be an even distribution of light with extra for hazardous areas. Ceilings and walls should be light coloured and non-reflective. Patients should face away from the window in daylight to avoid glare
• Local lighting - take into account inverse square law and also cosine law (put paper as close to 90 degrees to light source as possible to get maximum illuminance
• NB 60yr old needs 3 times the illumination of a 20 yr old due to senile miosis, media opacities and loss of neurons

Glare

• Discomfort Glare - subjective visual discomfort - px feels visually uncomfortable or fatigued. VA not affected by glare and discomfort relieved by tints. EG In uveitis, ocular albinism, cone-rod dystrophy, RP. Can be measured by getting patient to adjust light to a certain level of unpleasantness. No clinical relevance tho
• Disability Glare - Loss of retinal image contrast as a result of intraocular light scatter or stray light. This reduces visual performance. The degree of glare depends on the angle between the task and the glare source & the relative luminance
• Media opacs lead to IO light scatter and veiling luminance across retinal image and a reduction in contrast. Eg ageing, cataract, pos. chamber IOL, PCO, Keratoconus, Corneal Oedema, RK, vit opac

Disability glare can be measured objectively - px viewing an acuity/low contrast chart under controlled lighting conditions. This allows for simulation of everyday situations like flu overhead lighting, sunlight on cloudy day etc. Optom measures VA while shining penlight into pxs eye at a fixed distance and angle (eg 10cm and 30 degrees). Drop in VA of 2 lines or more indicates a significant degree of glare.

Reducing Disability Glare

• Environmental control, task lighting, avoidance of shiny surfaces, tints to reduce retinal illuminance, visors and hats
• People who may benefit from tint - media opac, albino, RP, Cone dystrophies, aniridia (though cone dystrophy may be better), corneal dystrophies, diabetics, uveitis
• Prescribe tints wrt subjective comfort or objective w/low contrast charts vs high contrast charts, varying illumination.

CIBSE Recommended levels for normally sighted px
(in lux)

• Living Room 50, Sewing/Sustained Reading 300, Kitchen 300, Hall/Stairs 150, Bathroom 50, Bedroom 50.
• 50-100% increase in those figures if you're over 65
• 5 times to 10 times increase if you're a VIP. Usually compromise w/1000 lux, adjustable

Bulbz

• Fluorescent is best. Gives poor colour rendering because usually at discreet wavelength but this is irrelevant in a low vision context.
• Discharge tube can be folded to give more compact bulb
• 9w or 11w, high efficacy
• Stays cool even after prolonged application
• NB Px can use any light source and it will not affect the way they read
  

Real Image/Transverse Magnification

M = SIZE OF IMG (on screen) / SIZE OF ORIGINAL OBJECT

CCTV is the most common way of producing this kinda magnification. It's aberration free (with magnification edge of magnifier view = rubbish) but the resolution of the screen determines image quality. Up to 70x mag is possible but usually about 30x is limit. The magnification is variable with a zoom control in a way that just ain't possible with an optical aid. This means if the px requires a change in magnification it remains useful. It has variable camera/task and eye/screen distances so allows for more normal viewing and extended reading. Reading speed is about the same though. Contrast etc is variable too.

Components

• Camera
• Light Source
• X-Y Platform
• Monitor screen (bigger screen = larger FOV - only 4 characters required for reading but up to 15 required for optimum page navigation)
• With the most common design (PORTABLE CCTV) each component is fixed and mounted vertically 'in line', working space is fixed or limited, all the controls are together so easier to set up. Also it's more portable duh.
• Can also add 2nd camera for distance

Advantages

• Zoom on magnification - overall view at low mag then increase for detail
• Adjustable mag if vision changes
• Monochrome/colour monitor allows for real life colour or different combinations
• Contrast reversal 0 >50% of px prefer white on black as it reduces scatter in media opacities
• Reading duration much increased but speed the same
• Binocular viewing from a normal distance
• More psychologically acceptable than a magnifier? Just looks like a computer if it's a kid@school
• Good if Parkinsons or something prevents optical aid usage
• Good if px has extensive vfd. Easier to adapt to steady eye strategy with it
• Split screen for simultaneous tasks

Disadvantages

• Expensive & need continuing service & repair
• Persistence of image on phosphor if CRT style screen
• Requires more practice than optical aids (15-20 sessions of daily practice)
• Bulky/obtrusive/difficult to move around - would need one for home and one for work
• Control posns often better for right handed
• Depth of field is limited (probs with thick books)

A head mounted device works in basically the same way. There are also TV readers which attach to the px's TV. The users of EVE aids are usually young & motivated. Px w/ VA>6/90 seem to gain little benefit from their use (mainly for reading, filling in forms, school tasks and viewing photos.

As regards to obtaining the visual aid, optical aids are usually provided by the HES - free to any px on permenant loan. There's no general formal scheme for electronic aids - they are bought privately. A registered VIP doesn't pay the VAT. Local charities or 'electronic aids for the blind' also supply but most are bought privately. They are available to use in libraries.

Tapermag

• Real image magnifier consisting of a bundle of transparent glass optical fibres
• Each fibre is narrow at the end which rests on the text and expands towards the top edge. The magnification is mainly real image magnification with a bit of relative distance magnification (the image is closer to the eye than the reading material)
• Aberration free but has a limited range of magnification (2.1-2.3x mag)
• Expensive compared to plus lens magnifiers.

LV: Visual Field Loss

This is broken down into central/peripheral field loss, with central always being associated with poor acuity.

Peripheral field loss can be caused by glaucoma or retinitis pigmentosa gradually over many years or sometimes cerebrovascular accident which causes homonymous hemianopia which is usually sudden onset due to a stroke or some other acute vascular lesion in the brain. That too can have a gradual onset if due to a tumour. Remember that any patient that has lost peripheral vision has lost rod cells so will have poor night vision.

Functional Effects

• A central field of 10 degrees or less significantly impairs mobility. When looking into the distance px isn't aware of the layout of his surroundings so bumps into things
• w/Intermediate vision it's difficult to get the whole task into view at the same time (TV/Computer) and finding objects on a cluttered desk is difficult
• w/reading px doesn't has trouble seeing ends of lines and starts of new ones

Other effects of hemianopia causing brain lesion

• Hemiplegia - difficult to posn/grip magnifier and/or task
• Loss of higher visual functions - agnosia (eg face recognition), alexia (reading)
• Oculomotor problems - squints, decomp phoria
• Personality/behaviour/attention change (drug induced maybe?)

Field Enhancement For Sighting

Reverse telescopes are used for tunnel vision but NOT hemianopia. They use magnification of less than 1 to fit more information into the available field. Acuity reduces in proportion. There's also something called an amorphic lens with minifies in the horizontal plane only, expanding the field in the area where it will be most useful while also preserving acuity. It is beneficial for scanning, finding things, viewing TV etc. They are fairly rare in the UK but are actually legal for driving in the US.

The px can also use a hand held minus lens which acts as if it's the -ve objective lens of a reverse telescope (the +ve eyepiece is the user's accommodation/bifocal). The higher power the lens, the bigger the field but smaller the acuity. Calculating the magnification uses the same telescopic eq as before M = -Fe/Fo where Fe is the accomm/add giving

M = 1 /(1-dFo)

Optimum lens diam = d x alpha (fov in degrees) / 60

Convex mirrors can be used in kitchen/hallway etc to detect people, open doors etc. Those ones that you see when you're in a different country going round a corner in the metro station. At the tube too actually come to think of it.

Field Enhancement For Mobility

There are various systems. First of all there's a hemianopia mirror which can be fixed or clipped onto existing specs. It projects objects from the missing field into the intact part of the patient's retina. This does create a blind spot where the mirror is blocking the normal view, but that area is seen by the other eye. It's again a convex mirror to expand the field and can be tinted to help distinguish direct and reflected images. Also it can be made semi reflecting so the view isn't totally obscured. Hemianopia mirrors aren't used very often.

A prism system is good for sufferers of RP and px w/bitemporal hemianopia w/<20degrees field and acuity better than 6/30. Stick on fresnel prism on the side of the lens closest to the defect base TOWARDS DEFECT with as much power as poss (15-30dioptres). Looking straight ahead the view is not affected. The problems with this system are the jump at the prism apex, the corresponding prism scotoma, and poor vision through the fresnel prism meaning you have to turn your head fully to critically examine the object. A fair bit of training is required. The prism should be placed in line with the edge of the pupil or limbus or at the edge of the measured field - 1mm on the spec lens is about equal to two degrees of field. You can assess this subjectively by moving a card across the lens until the px just notices it, then getting them to walk around a bit to make sure it isn't noticed.

Normally the prisms are fitted binocularly. Monocular is also possible, with the prism split vertically so the patient views through the centre of it. 30-40diop prism gets 20 degrees of field expansion and the patient never views through the prism so image degredation is not noticed. This requires little/no training and there isn't a prism scotoma. Other methods include full aperture (last resort) and InWave which is a field expanding channel lens. Also if you can't see the whole tv as part of your visual loss you could maybe just move the TV further away.

MANAGEMENT OF CENTRAL FIELD LOSS

Central field loss is a relatively common condition (ARMD, macular holes, CSR, Cystoid Macular Oedema, Toxic Maculopathies) and very disabling. It causes acuity loss impairing reading and face recognition, distortion, photostress, photophobia, depth perception problems, Charles Bonnet Syndrome. If the field loss is unilateral then the patient will usually just tend to ignore the worse eye and may not even realise the condition is present at first. Central field loss is only a problem if bilateral. As the fovea is involved acuity goes way down and images formed away from the fovea make the eye 're-foveate'. If viewing with one eye or suffering BCFL then the patient could be aware of a blank patch covering the object of regard if fixating centrally. Patient may use PRL just off the edge of the scotoma. Level of acuity there can be calculated. The available treatment methods are EV training, prism relocation and surgery.

Px w/central field loss

• Has a variety of magnifiers but can't really tell difference between them. Improvement with magnifier is less than expected and often reaches a plateau
  
• Has equal problems viewing newspaper headlines as small print
• Can read single letters or short words but can't even attempt long ones.

Eccentric Viewing

• This is heavily biased towards reading tasks. EV direction must be identified then practice w/SES commences
• Keep eye still & move text. This is easier than trying to refixate with an eccentric location on the retina. Also a good way of using a magnifier
• Treatment required a lot of follow-up visits/patience and is not often done
• First you have to locate the PRL with a scanning laser ophthalmoscope/video fundus camera, then use amsler grid, central field screeners etc and practice EV for faces, TV, looking at watch
• Lots of practice sessions are required - px uses printed sheets which get progressively more difficult - longer words, smaller letters, more words to a line. Should be done five minutes at a time a couple of times a day, warning px that they will feel very tired and improve slowly but there can be a great improvement over time
• Start with high power magnifier/small print or reading specs and bigger. May need to make magnifier less powerful as patient gets better

EV Training in Glasgow

• Px enters training programme after assessment @ GCU/Gartnavel/RAH
• LVA assessment by optoms with H&S, Refraction, mapping of scotoma, assessment of magnification needs using an Rx or hyperocular lens, assessment of suitability then referral
• Training - initial meeting, 1hr/week for 5 to 8 weeks, 5-10mins daily practice
• Trained using ZoomText, AceReader pro, lighting, typoscopes, hyperoculars, variety of texts
• Technique - use correct magnification, single eye technique, steady eye strategy, PRL, fixate on first letter or word them move text.

Prism Relocation

• Px fixating centrally - target imaged at scotoma. Need to find correct prism power and direction to place image on optimum PRL
• Do this by testing monocularly, using trial lenses for distance Rx and reading add for 20cm (can vary from +4.00 to +7.00 depending on px), putting prism in rotatable part of trial frame and getting px to rotate to find clearest vision on reading chart. If no improvement change prism power. When prism found try +/-0.50 power changes
• Prescribe - EG found N8 RE w/+6.00 & 4D at 90 and N24 LE w/+6.50 and 6D@150 then give +6.00 and 4D @90 both eyes.
• Reports suggest up is most common base direction
• Evidence for this working is scattered and unreliable, one study w/placebos found little difference
• Could argue that prism relocation has no theoretical basis - can't the px just refixate?

Surgical Treatment Options

• Macular Translocation Surgery
• w/wet AMD - detach and rotate retina, rotate globe in opposite direction.
• Still in research phase

Causes of central field loss

• AMD
• Best's Disease
• Stargardt's Disease
• Achromatopsia
• Cone dystrophies

Causes of peripheral field loss

• RP
• Strokes - hemianopia
• Chorioretinitis
• Glaucoma
• Aniridia
• Marfan's
• Ret det
• Leber's Amaurosis
• ON disorders eg optic atrophy
• Optic dysplasia and hypoplasia
  

More Common CL Complications

When there's staining in an area around the periphery of the lens it's likely to be one of two things. It could be lens binding which is more common in extended wear lenses, lenses that are too tight or px working in a dry atmosphere. It could also result from damage to the lens from fingernails/getting trapped in the case.

If there are particles visible underneath the lens it's often tear film debris. This is common in the sort of patient that just plonks their lenses in straight away in the morning. The debris will be visible under the slit lamp and will appear to be squashed down by the lens. If the debris is sleep debris then the patient isn't likely to notice it, but makeup has a more granular structure that will cause the lens to become uncomfortable. Mucin balls can be found under extended wear lenses - this is tear debris rolled into a ball by the movement of the lens.

CLPC

Symptoms include itchiness which worsens on removal of the lens. Also reduced wearing time. CLPC is a type IV delayed hypersensitivity reaction. There is a type I element too - the histamine response causing the itchiness.

CL wear should be discontinued for a good length of time - a guideline used = the efron grade of the CLPC x 2 = the number of months to discontinue wear.. EG grade 2 = discontinue for 4 months, assessing again 2 months in. Lens type should also be changed - dailies so that there are no further problems with denatured proteins. Also the lenses are thinner which minimises the mechanical action on the lids. You should expect improvement of at least 1 grade after a couple of months.

Mast cell stabilisers and anti=histamines can be used in the meantime to reduce symptoms as well as cold compresses. Some optoms actually just fit dailies straight away but if the CLPC is grade 2 or more that ain't going to work.

Flat Fitting RGP

Central abrasion that could ulcerate. Refit with steeper lens. The patient could wear the flat lens while the other lens is on order but

• minimise wearing time/wear specs when poss
• come straight back to practice if red eye/painful/blurry vision

Chronic Hypoxia corn neovasc

• Due to overwear, tight fit, lower H20 content lens
• Response = increase O2 transmission w/ultrathin lens/higher H20 content lens (NB consider whether PX will be able to wear higher water content lens in office with AC)

Steep Fitting RGP - Air Bubble?

• Could result in blinking w/froth + areas of dryness
• Fit flatter

Microcysts/Vacuoles

• Reversed light path = microcyst, unreversed = vacuole.
• Grade by counting numbers

Foreign Body

• Stromal diffusion of flu indicates deep!
• Give chloramphenicol every 2hrs for 12 hrs then 4x/day
• NB you have to take lenses out to put drops in, will px comply?
• See px in 24hrs, improvement? If not up dosage again or refer to hospital
• Check that foreign body isn't still around - slit lamp, under lids
• Need to work out cause, gardening accident? Could be something that could be avoided in the future
  

Glaucoma Care by Optoms in Bristol

This was another really good lecture! There was a HUGE amount of info in it that I can't hope to replicate here. Go back to the actual notes and read read read.

It's probably good to summarise glaucoma again. Hammer it in like. It's a variety of diseases with a common denominator - ACQUIRED PROGRESSIVE OPTIC NEUROPATHY. If it's untreated/unsufficiently treated it will lead to progressive loss of visual function. There are a variety of different causes and so a variety of different types/diagnoses. Let's categorise::::

• Open-Angle without ocular or systemic disorders - POAG, Normal Tension Glaucoma
• Angle closure without known ocular/systemic disorders - pupillary block glaucoma, combined mechanism glaucoma
• Developmental glaucomas - congenital, glaucomas assoc w/oc/systemic anomalies, 2ary glaucomas in childhood
• Glaucomas assoc w/oc/sys disorders - assoc w/disorders of endothelium, iris & cil body (pigmentary), lens, retina/choroid/vitreous, assoc w/intraocular tumours, elevated episcleral venous pressure, inflammation, steroid induced glaucoma, ocular trauma, haemorrhage, following intraoc surgery

Chronic Open Angle Glaucoma - Glau w/out ocular/systemic associations

• Epidemiology - onset from 35yr onwards, prevalence 2% (relatively common)
• Risk Factors - major ones are IOP and age, moderates are race and family history, minor are vasculopathy, vasospasm and lot central corneal thickness
• Subdivs - high pressure type (POAG), normal pressure type (Normal Tension Glau)
• Definition - multifactorial glaucoma w/characteristic progressive atrophy of ON head (not exactly sure of cause)
• Cause(s) - mechanical, vascular, autoimmune?
• Heredity - mostly unknown, few genes identified
• IOP Elevation - variety of angle degenerative changes
• Symptoms - none til advanced
• Signs - Physiological open angle, acquired disc/RNFL signs, VF signs
• Course - usually slowly progressive
• Visual prognosis is good cf age, how bad it is when first detected

Why should optoms take a greater involvement in glaucoma care?

• Causes blindness & visual morbidity
• Has substantial impact on the current NHS HES resources
• Optoms are already part of the pathway doing 95% of the glaucoma related referrals
• They have many of the tools/skills to equip them for an extended role
• The new prescribing legislation for optoms can be applied to glaucoma management
• College Glaucoma Higher Qualifications have been established
• NICE Glaucoma guidance is on the way
• The DoH trials of alternative glaucoma pathways have recently been completed
• International critical mass of glaucoma specialist optometrists

In 2004 'supplementary prescribers' were defined and in 2009 'independent prescribers'. Sup. prescribing extends the role of the prescriber to make better use of their knowledge and skills and is suitable for optometric co-management.

The Upcoming Clinical Challenge

Glaucoma is currently the second most common cause of CVI certifications. It has a better prognosis if treated in the disease's earlier stages. Early glaucoma is hard to identify. It's a chronic condition that requires lifelong review and is dominated by medical treatment. Obviously there is a public health issue as a significant proportion of cases may remain undetected.

The population of the UK is growing and ageing. There is expected to be a 12% growth in numbers and 8% shift towards the higher glaucoma prevalence age bracket (over 65 years). Life expectancy is also increasing (2002 women age 84, 2020 88) which obviously means more people having their glaucoma review. In summary, more people will be requiring more appointments for a longer period. Maths suggests that there'll be an extra 390,000 appts required per year by 2031 and current increases in ophthalmologist training are unlikely to meet this demand.

The Bristol Shared Care Scheme

Included peoples were glaucoma suspects, ocular hypertensives, stable/early/moderate POAG, PXF, Pigmentary Glau, px who can perform vf examinations, VA of 6/18 or better both eyes. People who are excluded - unstable glau, normal tension, 2ary glaus, narrow angle glau, any other existing ocular pathology, advanced VF loss and best corrected VA of 6/18 or less.

There was a study from 1993-1997 which showed that the optom and HES measurements were equally reliable and outcomes were comparable after two years of review. Px were more satisfied with having the check done at the local optom presumably because it was closer/easier to get to. The full cost of the assessments was cheaper if everyone was done at the hospital though. So after this study the scheme wasn't introduced. There was increased involvement of in house optoms within the Bristol eye hospital though

ARMD Referral - Is It Wet Or Dry?

Good guest lectures this week! Man yeah! This one was to refer/not to refer. Wet Vs Dry. There ain't no helping dry at this point. Wet can be helped by that lucentis thing that everyone reads about in the paper and gets all excited about. Lucentis inhibits VEGF-A which plays a critical role in the formation of new vessels which are responsible for the leakages.

Anyhoo, the RPE is critical in AMD. Drusen form in the RPE. Drusen are of course waste products of reactions in the retina that haven't been removed properly. They pile up in bulges. They have nothing to do with leaking blood vessels. In summary DRUSEN TAKE PLACE IN DRY AMD, ARE YELLOWISH, ROUND AND DEEP IN THE RETINA.

Stuff tagged as DRY

• Atrophic
• Drusen
• Geographic (kinda 'islands' of atrophy)
• RPE atrophy, changes

Stuff which is involved w/WET

• Exudative - stuff exudating out of blood vessels
  
• Disciform (round shaped fibrous scarring)
• Neovascular
• Choroidal Neovascular Membrane - network of all sorts of aberrant BV all over the place. More like a net/mesh

Exudates ain't drusen. They are higher up, hard edged and whiter. Another area of confusion is the Chorodial Neovasc Membrane. This membrane can either be

• Occult - hidden beneath the RPE so nothing visible to zap with PDT
• Classic - membrane has broken through the RPE and is visible

These days now lucentis is the main treatment that's replaced the laser so whether the membrane is occult or classic doesn't matter as much.

Various Things - To Refer Or Not

Oedema

• There are lots of causes of swelling at the macula, central serous retinopathy, cystoid macular oedema etc
• It's difficult to distinguish
• Which layer of the retina is raised?
• Try to avoid using oedema as a primary indicator of wet AMD

Amsler Chart - Distortions

• Distortion is a good indicator, but when the px mentions it before the amsler as opposed to when you're testing for it - the amsler is a very sensitive test. Drusen can raise the macula a bit causing a bit of distortion, as do PED and central serous retinop. In fact any macular disease can cause distortion.
• If the px is reading 6/9 N6 or better then they are highly unlikely to have treatable macular disease. No referral in that case, monitor!

Drusen

• Can be soft/hard
• More a risk factor for ARMD

Blood

• Shouldn't be any visible - leakage if there is - aberrant vessels
• Different from the background diabetic spots

Exudate

• Not good - indicates leaking aberrant vessels
• Could be present with or without visible blood
• Exudate is not treated directly, it's just a sign of potentially treatable new vessels

Exudates/Blood, refer!